Why Sun protection is important

Hair is primarily made of keratin, a fibrous protein that forms its structure and provides resilience. Understanding how the sun affects hair requires delving into its Anatomy. Hair is composed of three main layers:

1. The Cuticle: The outermost protective layer made up of overlapping, flat, dead keratin cells.

2. The Cortex: The thickest part of the hair shaft, consisting of fibrous keratin chains that give hair its strength and elasticity.

3. The Medulla: The innermost, sometimes hollow, core of the hair (not present in all hair types).

Each of these layers can be affected by prolonged exposure to ultraviolet (UV) radiation from the sun, specifically UVA and UVB rays.

UV Radiation and Its Impact on Hair Structure

Hair is primarily affected by two types of UV radiation:

-UVA Rays: These penetrate deeply into the cortex of the hair. Within the cortex lies melanin, the pigment responsible for hair color. UVA rays cause the oxidation of melanin, leading to the fading of natural and dyed hair. This oxidation disrupts the molecular structure of the pigment, resulting in a loss of vibrancy and a weakened cortex. Additionally, UVA radiation degrades disulfide bonds in keratin. These bonds are critical for maintaining hair’s strength and elasticity. As they break down, the hair becomes weaker and more prone to breakage.

UVB Rays: These primarily affect the cuticle, leading to protein degradation. UVB radiation weakens the keratin scales that form the protective outer layer, making hair porous and susceptible to moisture loss. As the cuticle becomes damaged, the hair shaft is exposed to external aggressors like pollution and chemicals, which further exacerbate dryness and roughness. Long-term UVB exposure causes cuticle scales to lift or peel away, leading to split ends, frizz, and an overall rough texture.

Internal Effects of UV Damage

Cortex Damage: Beyond melanin oxidation, the cortex consists of long chains of keratin proteins linked by hydrogen bonds, salt bridges, and disulfide bonds. UV radiation, particularly UVB, can break these bonds, causing the cortex to lose structural integrity. This leads to reduced tensile strength, making hair brittle and susceptible to snapping. The fiber damage caused by UVB rays results in reduced elasticity, making hair more difficult to style and manage.

Protein Degradation: Proteins in the cuticle and cortex, primarily keratin, undergo photodegradation upon UV exposure. This breakdown happens because the amino acids in keratin, like cysteine, are sensitive to UV radiation. Cysteine is rich in sulfur, which forms the disulfide bonds that give hair its resilience. When UV radiation disrupts these bonds, it results in protein oxidation, weakening hair strands. Over time, this leads to irreversible damage, making the hair more vulnerable to environmental stressors.

Lipid Depletion: Natural lipids (fatty acids) found in the cuticle play a crucial role in maintaining hair’s moisture balance and protecting it from external damage. Sun exposure strips away these lipids, reducing the hair’s hydrophobic properties and allowing water to escape more easily. This loss of moisture results in frizz, a rough texture, and difficulty in managing the hair.

Why UV Protection is Critical

Using a serum with UV protection is a scientifically backed method to prevent the degradation of the hair’s internal structure. These serums typically contain:

UV Filters (Physical and Chemical): UV-protectant serums often contain ingredients like octyl methoxycinnamate, titanium dioxide, or zinc oxide that either absorb or reflect UV radiation. These filters act as shields, preventing UV rays from reaching the cortex and cuticle.

Antioxidants: Ingredients like vitamin E and argan oil neutralize free radicals generated by UV exposure. Free radicals cause oxidative stress, accelerating the breakdown of keratin and melanin in the cortex. Antioxidants mitigate this process, protecting hair from oxidative damage.

Moisture Locking Agents: UV damage causes the hair to lose its moisture-retaining ability. Serums with humectants like glycerin or hyaluronic acid help replenish lost moisture and form a barrier that prevents further dehydration.

Protein Rebuilding Agents: Hydrolyzed keratin and amino acids in serums help repair the protein structure of the hair, restoring strength and elasticity. They work by filling in the gaps in the cuticle caused by protein degradation, smoothing the hair surface and reducing split ends.

In conclusion, UV radiation from the sun can severely damage the hair’s internal structure, degrading both proteins and lipids essential for maintaining healthy hair. Using a UV-protectant serum is crucial for shielding hair from the oxidative stress and moisture loss caused by the sun. The serum acts as a barrier, replenishing moisture, repairing protein damage, and preserving color, ensuring that your hair remains strong, vibrant, and healthy in the long term.

So it’s important to look for products that offer UV protection and help protect the hair from damage.